Extrusion lubricant

ABSTRACT

An extrusion lubricant comprising 2.5 to 30 percent graphite, 3 to 9 percent lead borate or zinc oxide, 10 to 15 percent sodium monophosphate or ammonium monophosphate, 1 to 5 percent wetting agent, up to 1 percent microbicide, and balance water.

I Unlted States Patent 1151 3,637,498 Sawyer [451 Jan. 25, 1972 54]EXTRUSION LUBRICANT 2,821,016 1/1958 Dickson ..252/29 2,986,492 5/1961Cannon .252/49.5 [721 lnvenm" Dav"! w-sawyefioakmmpa 3,230,750 1/1966Horbury etal ...252/28 73 Assigneez Ahlminum Company of America, pi3,278,429 10/1966 Agnew et al 252/59 sburgh, Pa. 3,341,454 9/1967 Choret al. ..252/29 Filed? P 29, 1963 Primary Examiner-Daniel E. WymanAssistant Examiner-l. Vau hn 21 A l.N 725156 8 1 pp 0 AttorneyAbram W.Hatcher [52] U.S.Cl ..252/30,72/42, 252/23, [57] ABSTRACT 252/495 511111. C1 ..c 10m 3/04, ClOm 3/02 gramme [58] Field of Search n 252/29 2330 72/42 3 to 9 percent lead borate or zinc oxide, 10 to 15 percentsodi- I um monophosphate or ammonium monophosphate, l to S [561References Cited percent wetting agent, up to 1 percent microbicide, and

balance water.

2 Claims, No Drawings l EXTRUSION LUBRICANT BACKGROUNDOF THE lNVENTlONThis invention relates to an extrusion lubricantiMore particularly, itrelates to a water-base extrusion lubricant adapted for application tobillet and dies to result in an improved surface finish on an extrudedmetal workpiece.

Until now problems have been many with respect to lubrication of diesand workpieces in formation of shaped articles from billets,particularly in extrusion operations on metals such as nonferrousmaterials like aluminum or aluminum base alloys. For example, it hasbeen difficult to find a lubricant which would be uniformly coated onthe die and workpiece surfaces to provide an adherent coating or film.Another problem has been how to develop a lubricant for extrusionpurposes which has a good stability or shelf life and which does notcontain solids which cause trouble by separating out or settling in sucha manner that when the lubricant is sprayed or applied to the die orworkpiece by dipping or spraying the resultant coating is too thin toprovide the desired adhering film.

U.S. Pat. No. 2,821,016 proposes a water solution containing arelatively small percentage of suspended colloidal graphite and from 1%to about 7 percent of a soluble oil as a cooling and lubricatingsolution for use in hot forging or extruding metal shapes. However, thewetting power of such a lubricant tends to be rather limited. US. Pat.No. 2,008,939 suggests coating metal with a concentrated aqueoussolution of monosodium phosphate or monoammonium phosphate and coldworking the metal while lubricated with this solution. While this patentteaches how the use of such a composition may help eliminate oily orinsoluble greasy metal soap depositswhich are difficult to remove fromthe workpiece, it lacks an efiicient lubricating component and makes nosuggestion as to how such a composition might be useful in extrusionsituations where high temperatures are commonly encountered. U.S. Pat.No. 2,530.838 discloses applying an aqueous solution of a synthetic wax,a metal borate and inert water-soluble organic lubricating binder towire or metal stock prior to a forming operation; This patent points outthat such. a composition providesa protective barrier film in wiredrawing but is silent as to any possible use of such a composition in anextrusion operation where a uniform film resistantto high temperaturesis required. Also, the patentee points out that in production ,oftherequired wax mixtures extreme caution has to used to insure that themelting point of the mixture is between about 95 C. and about 140 C.Therefore, development of an adhering, high-temperature resistantlubricant for application to either die or workpiece in the formation ofshaped metal articles by extrusion represents a highly desirable result.

STATEMENT OF THE INVENTION It is accordingly an object of this inventionto provide a lubricating composition which can be applied substantiallyunifonnly to both workpiece and die in extrusion operations. Anotherobject is to provide a lubricant of good shelf life and stability whichdoes not have any appreciable tendency for the solids therein toseparate out and one which is readily and uniformly dispensable. Afurther object is to provide an extrusion lubricant which is capable ofwithstanding high temperatures, specifically up to about 1,050" F.without substantial decomposition or loss of the required protectivefilm. A still further object is to provide a lubricant which can beapplied to either billet or dies or both with a resulting improvedsurface finish on the extruded product. Another object is to provide alubricant which when applied .cold to billets will withstand subsequenttemperatures as high as 1,050 F. These and other objects of ourinvention will be apparent from the description and claims which follow.

This invention is predicated upon the discovery that an improvedlubricating composition for use in metal extrusion operations can beprepared by blending together 2.5 to 30 .fonated mineral oils, alkylaryl percent by weight colloidal graphite, 3 to 9 percent by weight leadborate or zinc oxide, 10 to 15 percent sodium monophosphate or ammoniummonophosphate, l to 5 percent of a wetting agent such as an organicsulfonate, up to 1 percent by weight microbicide and water. While thiscomposition may be applied onlyto ingot or only to die according to myinvention, l prefer to use it on both ingot and die. My preferredcomposition contains 18 to 25 percent graphite, 5 to 7 percent leadborate or zinc oxide, 11.5 to 14 percent ammonium monophosphate orsodium monophosphate, 1.5 to 3.5 percent wetting agent, up to about 0.5percent microbicide and 45 to 65 percent water. ln preparing mylubricant, l have found it advantageous to first blend the colloidalgraphite in the form of a dispersion of about 28 percent graphite inwater with the ammonium or sodium monophosphate, the wetting agentand'the microbicide before adding the lead borate or zinc oxide.

The size of the colloidal graphite is preferably such that at least 50percent of the particlesare 2.5 microns or less in average diameter.Representative of wetting agents which l have found useful in myextrusion lubricant are organic sulfonates such as the sodium salt ofpetroleum sulfonates, sulsulfonates, and substituted benzyl alkylsulfonic acids.

The following examples are illustrative of my invention. The followinglubricant were applied to dies and billets in forming shaped articles byextrusion of billets through die cavities. The dies and billets used hada substantially uniform film of the lubricant coated thereon in eachcase. Extrusion temperatures ranged from 600 to l,100 F. No ram flashingwas encountered. Percent herein refers to percent by weight.

EXAMPLE 1 4.8% graphite (2.5 microns) 6% lead borate l2.7% ammoniummonophosphate 2.8% wetting agent (a substituted benzyl alkyl sulfonicacid) 73.7% water EXAMPLE 2 4.8% graphite (2.5 microns) 6% lead boratel2.7% ammonium monophosphate 2.8% wetting agent (a substituted benzylalkyl sulfonic acid) 73.6% water 0.1% microbicide EXAMPLE 3 22% graphite(2.5 microns) 6% lead borate l 2.7% ammonium monophosphate 2.8% wettingagent (a substituted benzyl alkyl sulfonic acid) 56.4% water O.%microbicide EXAMPLE 4 21.7% graphite (mostly 1 micron but some particlesless than 0.5 micron in average diameter) 12.7% ammonium monophosphate6.0% borate 2.8% wetting agent (a substituted benzyl alkyl sulfonicacid) 56.8% water EXAMPLE 5 21.7% graphite (2.5 microns) 12.8% ammoniummonophosphate 6.0% lead borate 2.8% wetting agent(a substituted benzylalkyl sulfonic acid) 6.0% microbicide 56.7% water EXAMPLE 6 22% graphite(2.5 microns) 12.7% ammonium monophosphate 6.0% lead borate 2.8% wettingagent (a substituted benzyl alkyl sulfonic acid) 0.1% microbicide 56.4%water EXAMPLE 22% graphite (2.5 microns) 12.7% monobasic sodiumphosphate 6.0% lead borate 2.8% wetting agent (a substituted benzylalkyl sulfonic acid) 0.1% microbicide 56.4% water EXAMPLE 8 22% graphite(2.5 microns) 12.7% ammonium monophosphate 6.0% zinc oxide 2.8% wettingagent (a substituted benzyl alkyl sulfonic acid) 0.1% microbicide 56.4%water EXAMPLE 9 22% graphite (2.5 microns) 12.7% monobasic sodiumphosphate 6.0% zinc oxide 2.8% wetting agent (a substituted benzyl alkylsulfonic acid) 0.1% microbicide 56.4% water Lubricants were prepared andused in extrusion operations (coated on billets and dies) and hadsubstantially the same compositions as the lubricants of examples 6, 7,8 and 9 except that the following wetting agents were used individuallyin separate formulations instead of the substituted benzyl alkylsulfonic acid of examples 1-8:

sodium salt of petroleum sulfonate sulfonated mineral oil alkyl arylsulfonate All resulted in an adherence which was comparable to that forthe formulations which used the substituted benzyl alkyl sulfonic acidwetting agent.

While the invention has been described in terms of preferredembodiments, the claims appended hereto are intended to encompass allembodiments which fall within the spirit of the invention.

Having thus described my invention and certain embodiments thereof, Iclaim:

1. An extrusion lubricant consisting essentially of 2.5 to 30 percent byweight colloidal graphite, 3 to 9 percent by weight lead borate or zincoxide, 10 to 15 percent by weight sodium monophosphate or ammoniummonophosphate, 1 to 5 percent by weight wetting agent, up to 1 percentmicrobicide, and balance water.

2. The lubricant of claim 1 wherein the colloidal graphite comprises18-25 percent by weight, the lead borate or zinc oxide 5-7 percent byweight, the sodium monophosphate or ammonium monophosphate 1.5 to 3.5percent by weight and the water 45 to 65 percent by weight.

2. The lubricant of claim 1 wherein the colloidal graphite comprises18-25 percent by weight, the lead borate or zinc oxide 5-7 percent byweight, the sodium monophosphate or ammonium monophosphate 1.5 to 3.5percent by weight and the water 45 to 65 percent by weight.